Lubricating oil composition

ABSTRACT

Lubricating oil composition containing an ashless rust inhibitor prepared from a reaction of glycerol with a C8 to C25 alpha olefin epoxide.

United States Patent 191 Haugen et al.

LUBRICATING OIL COMPOSITION Inventors: Haakon Haugen, Oslo, Norway;

David G. Weetman, Hopewell Junction, N.Y.

Assignee: Texaco, Inc., New York, NY.

Filed: Dec. 15, 1972 Appl. No.2 315,382

US. Cl. 252/52 R, 252/396, 260/615 R Int. Cl C10m 1/22 Field of Search 252/52 R, 52 A, 396;

References Cited UNITED STATES PATENTS 8/1962 Gaertner 252/52 R x Primary ExaminerW. Cannon Attorney, Agent, or Firm-T. H. Whaley; C. G. Ries [5 7 ABSTRACT Lubricating oil composition containing an ashless rust inhibitor prepared from a reaction of glycerol with a C to C alpha olefin epoxide.

8 Claims, N0 Drawings LUBRICATING OIL COMPOSITION BACKGROUND OF THE INVENTION This invention is concerned with a lubricating oil composition particularly useful as a motor oil containing an ashless rust inhibitor.

An important development in the lubricating oil additive field has been use of ashless additives, i.e., additives which are free of metal and yet are capable of providing necessary lubricating oil properties. An outstanding feature of the ashless additives is the avoidance of the formation of ash when the additive decomposes during the operation of the engine. Deposits in the intake manifold and in the combustion zone are minimized by the use of ashless additives in the motor oil.

SUMMARY OF THE INVENTION The novel ashless anti-rust additive of the invention is an alkyl ether derived from glycerol; the alkyl group is substituted with a hydroxyl group. This additive is represented by the following generic formula:

(EH --X CH-O-Y Gil -OH in which X and Y alternately represent hydrogen, and the radical;

in which R is an alkyl group having from about 6 to 23 carbon atoms. The two structures for the anti-rust additive coming within the generic formula are represented in which R has the value noted above.

The anti-rust additive of the invention is prepared by reacting glycerol with an alpha olefin epoxide to effect an alkoxylation reaction at one of the hydroxyl groups of glycerol. The desired reaction is between one mole of glycerol and a mole of the alpha olefin epoxide. This is accomplished by employing up to one mole of the epoxide per mole of glycerol being careful to avoid any significant excess of the epoxide.

The alkylene oxide or alpha olefin epoxide compound employed in this reaction is represented by the following formula:

in which R is an alkyl group having from about 6 to about 23 carbon atoms. The preferred alpha olefin epoxide compounds are those in which the alkyl group or radical represented by R has from about 9 to about 16 carbon atoms.

Commercially available mixtures of alpha olefin epoxides, such as a mixture of straight chain C C and C C alpha olefin epoxides, are particularly convenient for preparing the additive of this invention.

In general, the reaction is conducted by reacting approximately one mole of alpha olefin epoxide with a mole of glycerol at an elevated temperature to effect alkoxylation at one of the hydroxyl groups in the glycerol. While it is preferred to conduct this reaction employing approximately one mole of the alpha olefin epoxide with one mole of glycerol, the reaction can be conducted employing a reduced proportion of the epoxide. Indeed, the mole ratio of epoxide to glycerol can range from about 0.10 to 1.0 to a mole of glycerol. It is important to avoid an excess of the epoxide in order to avoid alkoxylation of more than one portion of the glycerol. This reaction is assisted by the presence of an alkaline catalyst, such as an alkaline earth oxide including calcium oxide, etc. The reaction is also promoted using an elevated temperature ranging from about to 200 C. with the preferred temperature being from to about 180 C.

It will be appreciated that two isomers of the hydroxyalkylether of glycerol can be produced in the noted reaction. Either isomer is effective as a lubricating oil additive and the isomeric mixture itself can be employed for this purpose.

Specific examples of these compounds include the following:

2-[2-hydroxyoctyloxy1-l ,3-propanediol 2-[2-hydroxydecyloxy]-l ,3-propanediol 2-[2-hydroxydodecyloxy]-1,3-propanediol 2-[2-hydroxy-4 ethyloctyloxyl-l ,3-propanediol 2-[2-hydroxyoctadecyloxy]-1,3-propanediol 2-[2-hydroxyhexadecyloxy1-1,3-propanediol 3-[ 2-hydroxynonyloxy]- 1 ,2-propanediol 3-[2-hydroxydecyloxy1-l ,2-propanediol 3-[2-hydroxyoctadecyloxy]-1,2-propanediol 3-[2-hydroxy-4-ethyldodecyloxy ]-l ,2-propanediol 3-[2-hydroxytetradecyloxy1-1,2-propanediol 3-[2-hydroxycetyloxy1-l ,2-propanediol The lubricating oil composition of the invention will comprise a hydrocarbon base oil containing a minor amount of anti-rust additive of the prescribed hydroxyalkyl substituted ether of glycerol. The hydrocarbon base oil employed herein is generally a mineral oil and can be derived from a paraffin base, napthene base or mixed paraffin -naphthene base distillate or residual oils. Paraffin base distillate lubricating oil fractions are preferred for the formulation of premium lubricating oil compositions such as are contemplated in this invention. A lubricating oil composition consisting essentially of the hydrocarbon base oil and the prescribed anti-rust additive is useful under some conditions.

The lubricating oil base will have been subjected to solvent refining to improve its lubricity and viscosity temperature relationship, as well as to solvent dewaxing to remove waxy components and improve the pour point of the oil. Generally, mineral lubricating oil bases having an SUS Viscosity at 100 F. between 50 and 1,000 can be used in the formulation of the improved lubricants of the invention. The viscosity of the preferred base oil will usually fall between 70 and 300 SUS at 100 F. A blend of base oils can be employed to provide a suitable base for a multigrade motor oil.

The concentration of the anti-rust additive in the lubricating oil composition of the invention will broadly range from about 0.05 to 1.0 weight percent. A particularly effective concentration for the anti-rust additive is from about 0.1 to 0.75 weight percent with the preferred concentration ranging from 0.25 to 0.60 percent.

EXAMPLE 1 Preparation of the C to C Hydroxyalkyl Ether of Glycerol 195 grams of C ,C alpha olefin epoxide mixture (1.0 mole) and 552 grams of glycerol (6.0 moles) and 2.0 grams of calcium oxide were placed in a flask equipped with a stirrer and heated to 180 C. After about 4 hours, the reaction product was cooled to room temperature. The layers which formed were separated. The upper layer of 347 grams was heated to 125 C. under a vacuum of 0.5 to 0.01 millimeters of mercury to remove unreacted glycerol. To insure the removal of all of the glycerol, the distillation residue was diluted with diethyl ether (500 ml) and extracted with water. The etherial layer was dried with anhydrous magnesium sulfate, reduced in volume in a rotary evaporator and heated to 140 C. under a vacuum of 0.4 to 0.1 mm. of mercury. The residue weighed 180 grams.

Analysis of the C to C alkoxylated glycerol gave the following results:

Theory Found Hydroxyl No. 585 563 Molecular weight 287 270 EXAMPLE ll Theory Found Molecular Weight 334 344 Hydroxyl No. 490 441 A lubricating oil composition of the invention adapted for use as a crankcase motor oil will contain a balanced blend of conventional motor oil additives to viscosity index improvement, oxidation and corrosion resistance, dispersancy and alkalinity reserve.

A mono-hydroxyalkyl hydrocarbyl thiophosphonate can be employed as an ashless dispersant additive in the lubricant composition of this invention. These compounds are prepared by reacting an alkylene oxide with a hydrocarbyl thiophosphonic acid obtained from a hydrocarbon-P S reaction product by hydrolysis with steam and subsequent treatment of the hydrolyzed product to remove inorganic phosphorus acids. The action of alkylene oxide with the hydrocarbyl thiophosphonic acid is effected at temperatures between about 60 and 150 C. and heating under reflux for a period of time ranging from 0.5-2.0 hours. The reaction mixture is then blown with an inert gas, such as nitrogen, at a temperature between about and C. until the product is dry and free of unreacted alkylene oxide.

The hydrocarbyl thiophosphonic acids employed in preparing the mono-hydroxyalkyl thiophosphate employed as a lubricant additive may be represented by the general formula:

R-POH l on wherein R is a hydrocarbyl group which may be aromatic, aliphatic or cycloaliphatic in nature and which usually contains 12 or more carbon atoms and X is sulfur or a mixture of a major portion of sulfur and a minor portion of oxygen. The alkyl group (R) in this formula is advantageously a polyolefin chain such as polyisobutylene or polypropylene having an average molecular weight between about 250 and 50,000 since such materials are the preferred materials for reaction with P 3 The preferred hydrocarbyl group is a polybutene having a molecular weight between 600 and 5000. The preparation of the thiophosphonate derivatives is disclosed in detail in U.S. Pat. No. 3,272,744.

In general, a formulated motor oil of the invention will contain from about 1.4 to 4.0 weight percent, amounts corresponding to about 0.035 to 0.10 weight percent of elemental phosphorus, of the abovedescribed thiophosphonate. The preferred amount of the thiophosphonate is from 1.8 to 3.2 weight percent. Commercial succinimide type dispersants can also be employed such as those described in U.S. Pat. No. 3,172,892.

An effective viscosity index improver for a crankcase motor oil is an oil-soluble, basic amino nitrogencontaining addition-type polymer commonly referred to as methacrylate copolymer, comprising a plurality of polymerizable ethylenically unsaturated compounds, at least one of which is amino-free and contains from 8 to about 18 carbon atoms in an aliphatic hydrocarbon chain, preferably predominantly straight chain in nature, and one of which as it exists in the polymer contains a basic amino nitrogen in the side chain, said polymer containing 0.05 to 3.5 weight percent thereof of basic amino nitrogen. The method of preparing these polymers is described in detail in U.S. Pat. No. 2,737,496. Other known viscosity index improvers, such as ethylenepropylene copolymers, can also be used.

In general, a formulated motor oil will contain from about 1 to 15 weight percent, preferably 1.5 to 7 percent, of the viscosity index improver.

Certain alkaline earth metal salts are usually added to lubricating oil compositions as detergents. Useful in this regard are the alkaline earth metal alkyl phenolates and sulfonates, such as barium nonyl phenolate. barium dodecyl phenolate, calcium sulfonate and calcium dodecyl phenolate. These compounds are usually employed in a concentration from about 0.1 to 5.0 weight percent.

Another class of valuable additives for a formulated motor oil is zinc dialkyl dithiophosphates which function as oxidation and corrosion inhibitors. Examples of these compounds are zinc isobutyl Z-ethylhexyl dithiophosphate zinc di(2-ethylhexyl) dithiophosphate, zinc isoamyl 2-ethylbutyl dithiophosphate and zinc diconventional methacrylate tetrapolymer formed from butyl-, lauryl-, stearyland dimethylaminoethyl methacrylates viscosity index improver, a mono-(B- hydroxyethyl) alkane phosphonate dispersant, a zinc dialkyldithiophosphate antioxidant, anti-wear agent and a diethyl-tert-dioctyldiphenylamine oxidation inhibitor. The balance of the oil formulation and the test results are set forth in the table below.

TABLE 1 MS-ll C TEST Oil Composition (dodecyl) dithiophosphate. These inhibitors are effective in lubricating oil compositions when employed in a concentration ranging from about 0.1 to 5.0 weight percent.

Other suitable anti-oxidants for a motor oil are the aromatic amines such as phenylenediamine, diphenylamine and napthylamine and their aliphatic hydrocarbon derivatives in which the alkyl groups have from 1 to 16 carbon atoms. Diethyl dioctyldiphenylamine is a particularly effective antioxidant. These additives are generally employed at a concentration ranging from about 0.05 to 4.0 weight percent of the composition.

The rust-inhibiting property of the lubricant of the invention was determined in the MS-ll C Test which is described in the current General Motors Engineering Standard GM 6041M. Briefly, this test employs a modified Oldsmobile V-8 Engine with cooled valve cover jackets, a cooled crossover and a knock back condenser to return corrosive elements to the crankcase. The conditions of this test are those of very severe low temperature operation. The fuel employed is highly leaded (4 cc/gal) and doctored with di-t-butyldisulfide to 0.07 percent sulfur. The operating parameters are shown below:

Fuel GMR 995, 4.0 cc/gal TEL, 0.07% sulfur Oil to engine 120 F.

Coolant, jacket out 110 F.

Coolant, crossover out 109 F.

Air fuel ratio 13.0

Blowby rate 0.8 CFM Test duration 32 hours The lubricant of the invention was tested in a base blend consisting of a mineral base oil and conventional motor oil additive. The mineral base oil had the following inspection values:

Gravity, API 308 Flash. COC F. 415 Viscosity. SSU at 0 F. (extrap.) 6015 Viscosity. SSU at 100 F. 160 Viscosity, SSU at 210 F. 43.9

The base blend employed in all the examples consisted of the above-described base oil and contained a CH-O-Y CH -OH in which X and Y alternatively represent hydrogen and a hydroxy-substituted radical having the formula:

in which R is an aliphatic hydrocarbon radical having from about 6 to 23 carbon atoms, one of X and Y being said hydroxy-substituted radical.

2. A lubricating composition comprising a mineral lubricating oil as a major component and containing from about 0.1 to 0.75 weight percent of an additive having the formula:

( H -0-CH fill-R JH-OH 0H CH -OH in which R is an aliphatic hydrocarbon radical having from about 9 to 16 carbon atoms.

3. A lubricating composition comprising a mineral lubricating oil as a major component and containing from about 0.1 to 0.75 weight percent of an additive having the formula:

6. A lubricating composition according to claim 1 in which said additive is 3-[2-hydroxytetradecyloxy]l ,2- propanediol.

7. A lubricating composition according to claim 1 in which said additive is 3-[2-hydroxyoctadecyloxy]-l,2- propanediol.

8. A lubricating composition according to claim 1 in which said lubricating oil is a mineral lubricating oil having an SUS viscosity at F. between 50 and 1000. 

1. A LUBRICATING COMPOSITION COMPRISING A LUBRICANT OIL AS A MAJOR COMPONENT AND CONTAINING FROM ABOUT 0.05 TO 1.0 WEIGHT PERCENT OF AN ADDITIVE REPRESENTED BY THE FORMULA:
 2. A lubricating composition comprising a mineral lubricating oil as a major component and containing from about 0.1 to 0.75 weight percent of an additive having the formula:
 3. A lubricating composition comprising a mineral lubricating oil as a major component and containing from about 0.1 to 0.75 weight percent of an additive having the formula:
 4. A lubricating composition according to claim 1 in which said additive is 2-(2-hydroxyhexadecyloxy)-1,3-propanediol.
 5. A lubricating composition according to claim 1 in which said additive is 2-(2-hydroxyoctadecyloxy)-1,3-propanediol.
 6. A lubricating composition according to claim 1 in which said additive is 3-(2-hydroxytetradecyloxy)-1,2-propanediol.
 7. A lubricating composition according to claim 1 in which said additive is 3-(2-hydroxyoctadecyloxy)-1,2-propanediol.
 8. A lubricating composition according to claim 1 in which said lubricating oil is a mineral lubricating oil having an SUS viscosity at 100* F. between 50 and
 1000. 